Polyolefin resin pellets and method for producing the same

Abstract

An object of the present invention is to provide a polyolefin resin pellet with less generation of fine powder. A pellet which is a polyolefin resin pellet containing a polyolefin resin, erucic acid amide, and a fatty acid amide having 20 or less carbon atoms, wherein when the total amount of the erucic acid amide and the fatty acid amide having 20 or less carbon atoms is set to 100% by mass, the content of the fatty acid amide having 20 or less carbon atoms is 1% to 6% by mass.

Description

Technical Field

[0001] The present invention relates to polyolefin resin pellets and a method for manufacturing the same. Background Art

[0002] From the viewpoints of good durability and workability, polyolefin resins are used for packaging materials such as plastic bags, and such packaging materials are manufactured by extrusion molding a polyolefin resin film.

[0003] As a characteristic required for a polyolefin resin film, there is slipperiness. When the slipperiness is poor, problems such as the wound films adhering to each other and not being able to be peeled off, or the film adhering to the extrusion molding machine during extrusion molding of the film and not being able to be peeled off occur.

[0004] Therefore, in order to improve the slipperiness of a polyolefin resin film, a lubricant has been conventionally added to the polyolefin resin as a film material. For example, an organic fatty acid amide-based lubricant is used in the method of Patent Document 1.

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: Japanese Patent Laid-Open No. 2001-72810 Summary of the Invention

[0008] Problems to be Solved by the Invention

[0009] A polyolefin resin film is manufactured by subjecting polyolefin resin pellets to molding processing to form a film.

[0010] The resin pellets can be obtained by melting and kneading the resin and then extrusion molding. The lubricant for improving the slipperiness of the film can be added during the melting and kneading of the resin.

[0011] However, the present inventors have found that when erucamide, which is an organic fatty acid amide, is used as a lubricant, the manufactured resin pellets are easily ground, and fine powder is generated from the fragments of the ground resin pellets. When such resin pellets attached with or mixed with fine powder are used, there is a problem that the subsequent moldability is reduced.

[0012] Therefore, an object of the present invention is to provide polyolefin resin pellets that generate less fine powder.

[0013] Means for Solving the Problems

[0014] The present inventors have conducted intensive studies and as a result, have found that the generation of fine powder in polyolefin resin pellets containing erucamide and a fatty acid amide having 20 or less carbon atoms in a specific ratio is reduced, and thus the present invention has been completed.

[0015] That is, the present invention is described as follows. [1]

[0017] A pellet, which is a polyolefin resin pellet containing a polyolefin resin, erucamide, and a fatty acid amide having 20 or less carbon atoms, wherein

[0018] when the total amount of the erucamide and the fatty acid amide having 20 or less carbon atoms is 100% by mass, the content of the fatty acid amide having 20 or less carbon atoms is 1% to 6% by mass. [2]

[0020] The pellet according to [1], wherein the polyolefin resin is one or more selected from polyethylene resins and polypropylene resins. [3]

[0022] The pellet according to [1] or [2], wherein the fatty acid amide having 20 or less carbon atoms contains both an unsaturated fatty acid amide and a saturated fatty acid amide. [4]

[0024] The pellet according to [3], wherein the ratio of the content of the unsaturated fatty acid amide contained in the fatty acid amide having 20 or less carbon atoms to the content of the saturated fatty acid amide is 2 to 6. [5]

[0026] The pellet according to any one of [1] to [4], wherein when the total amount of the erucamide and the fatty acid amide having 20 or less carbon atoms is 100% by mass, the content of the unsaturated fatty acid amide having 20 or less carbon atoms is 1.0% to 6.0% by mass. [6]

[0028] The pellet according to any one of [3] to [5], wherein the unsaturated fatty acid amide is a monounsaturated fatty acid amide. [7]

[0030] The pellet according to any one of [3] to [6], wherein the unsaturated fatty acid amide is one or more selected from oleic acid amide and gadoleic acid amide. [8]

[0032] The pellet according to any one of [1] to [7], wherein when the total amount of the erucamide and the fatty acid amide having 20 or less carbon atoms is 100% by mass, the content of the saturated fatty acid amide having 20 or less carbon atoms is 0.3% to 1.0% by mass. [9]

[0034] The pellet according to any one of [3] to [8], wherein the saturated fatty acid amide is one or more selected from the group consisting of capric acid amide, palmitic acid amide, stearic acid amide, and arachidic acid amide.

[10]

[0036] The pellet according to any one of [1] to [9], wherein the pellet further contains a fatty acid amide having 22 or more carbon atoms other than erucic acid amide.

[11]

[0038] The pellet according to

[10] , wherein the fatty acid amide having 22 or more carbon atoms is one or more selected from the group consisting of behenic acid amide, selacholeic acid amide, and lignoceric acid amide.

[12]

[0040] A method for manufacturing a resin pellet, which is a method for manufacturing a polyolefin resin pellet according to any one of [1] to

[11] , wherein

[0041] The method for manufacturing the resin pellet includes:

[0042] A step of mixing a polyolefin resin and a lubricant to obtain a mixture, and

[0043] A step of melt-extruding the mixture to obtain resin pellets,

[0044] The lubricant contains erucic acid amide and a fatty acid amide having 20 or less carbon atoms, and

[0045] When the total amount of the erucic acid amide and the fatty acid amide having 20 or less carbon atoms is set to 100% by mass, the content of the fatty acid amide having 20 or less carbon atoms is 1% to 6% by mass.

[0046] Advantages of the Invention

[0047] According to the present invention, it is possible to provide polyolefin resin pellets with less generation of fine powder. Detailed Description of the Invention

[0048] <Polyolefin Resin Pellets>

[0049] Hereinafter, the polyolefin resin pellets of the present embodiment will be described in detail.

[0050] The polyolefin resin pellets of the present embodiment contain a polyolefin resin, erucic acid amide, and a fatty acid amide having 20 or less carbon atoms.

[0051] (Polyolefin Resin)

[0052] The polyolefin resin contained in the polyolefin resin pellets of the present embodiment is not particularly limited as long as it is a resin containing a polymer obtained by polymerizing an olefin as a monomer. For example, polyethylene resins and polypropylene resins can be mentioned.

[0053] (Polyethylene resins)

[0054] Polyethylene resins include ethylene polymers. Examples of ethylene polymers are ethylene homopolymers, copolymers of ethylene and α-olefins, and copolymers of α-olefins substituted with alicyclic compounds and ethylene.

[0055] Examples of ethylene homopolymers are low-density polyethylene (LDPE) by the high-pressure method with a density of 910 kg / m 3 ~935 kg / m 3 which is obtained by using a radical initiator and bonding ethylene of the repeating unit randomly and with a branched structure by high-pressure radical polymerization.

[0056] Examples of copolymers of ethylene and α-olefins include linear low-density polyethylene having crystallinity, ethylene and α-olefin copolymer elastomers having low crystallinity and rubber-like elastic properties, etc.

[0057] The density of linear low-density polyethylene can be 900 kg / m 3 ~940 kg / m 3 and the density of the ethylene and α-olefin copolymer elastomer can be 860 kg / m 3 ~900 kg / m 3 .

[0058] Examples of α-olefins are α-olefins having 3 to 10 carbon atoms. As α-olefins having 3 to 10 carbon atoms, for example, propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 3-methyl-1-butene, etc. can be mentioned. α-olefins having 4 to 10 carbon atoms are preferred, and 1-butene, 1-hexene or 1-octene are more preferred.

[0059] Examples of α-olefins substituted with alicyclic compounds are vinylcyclohexane.

[0060] The amount of the structural unit derived from the α-olefin in the ethylene polymer can be 4.0 mass% to 20 mass%.

[0061] Specific examples of the copolymer of ethylene and an α-olefin are ethylene-1-butene copolymer, ethylene-1-hexene copolymer, ethylene-1-octene copolymer, ethylene-1-decene copolymer, ethylene-(3-methyl-1-butene) copolymer. These copolymers can be a single kind or a mixture of two or more kinds. In addition, the ethylene-based polymer can be a mixture of a homopolymer of ethylene and a copolymer of ethylene and an α-olefin.

[0062] The melt flow rate of the ethylene-based polymer measured at a temperature of 190 °C under a load of 2.16 kg can be 0.5 g / 10 min to 50 g / 10 min, preferably 1 g / 10 min to 30 g / 10 min, more preferably 1 g / 10 min to 20 g / 10 min.

[0063] The ethylene-based polymer can be produced using a known polymerization catalyst by a known polymerization method.

[0064] As the polymerization catalyst, for example, homogeneous catalyst systems represented by metallocene catalysts, Ziegler-type catalyst systems, Ziegler-Natta-type catalyst systems, etc. can be cited. As the homogeneous catalyst system, for example, a catalyst system containing a transition metal compound of Group 4 of the periodic table having a cyclopentadienyl ring and an alkylaluminoxane; or a catalyst system containing a transition metal compound of Group 4 of the periodic table having a cyclopentadienyl ring, a compound that forms an ionic complex by reacting with the transition metal compound, and an organoaluminum compound; a catalyst system obtained by modifying catalyst components such as a transition metal compound of Group 4 of the periodic table having a cyclopentadienyl ring, a compound that forms an ionic complex, and an organoaluminum compound supported on inorganic particles such as silica and clay minerals, etc. In addition, a prepolymerization catalyst prepared by prepolymerizing ethylene and an α-olefin in the presence of the above catalyst system can also be used.

[0065] In addition, high-pressure low-density polyethylene (LDPE) can be produced using a radical initiator as a polymerization catalyst.

[0066] (Polypropylene resin)

[0067] The polypropylene resin contains a polypropylene-based polymer. Examples of the polypropylene-based polymer are a homopolymer of propylene, a copolymer of ethylene and / or an α-olefin having 4 to 10 carbon atoms and propylene.

[0068] The melt flow rate of the propylene homopolymer measured at a temperature of 230 °C under a load of 2.16 kg can be 0.1 g / 10 min to 50 g / 10 min.

[0069] The melt flow rate (MFR) of a copolymer of ethylene and / or an α-olefin having 4 to 10 carbon atoms and propylene, measured at a temperature of 230 °C under a load of 2.16 kg, can be from 10 g / 10 min to 200 g / 10 min.

[0070] When the total mass of the copolymer of ethylene and / or an α-olefin having 4 to 10 carbon atoms and propylene is set to 100% by mass, the structural unit derived from ethylene and / or an α-olefin having 4 to 10 carbon atoms can be from 0.1% by weight to 40% by weight, and the structural unit derived from propylene can be from 99.9% by weight to 60% by weight.

[0071] In this specification, the "structural unit" in the term "structural unit derived from ethylene" refers to the polymerization unit of the monomer. Thus, for example, the "structural unit derived from ethylene" refers to the structural unit of -CH2CH2-.

[0072] Examples of the α-olefin having 4 to 10 carbon atoms include 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, etc., and 1-butene, 1-hexene or 1-octene is preferred.

[0073] Specific examples of the copolymer of ethylene and / or an α-olefin having 4 to 10 carbon atoms and propylene include a random copolymer of propylene and ethylene, a random copolymer of propylene and an α-olefin having 4 to 10 carbon atoms, a random copolymer of propylene, ethylene and an α-olefin having 4 to 10 carbon atoms, a propylene block copolymer, etc. These copolymers can be used alone or as a mixture of two or more. In addition, the propylene polymer can be a mixture of a propylene homopolymer and a copolymer of ethylene and / or an α-olefin having 4 to 10 carbon atoms and propylene.

[0074] Examples of the random copolymer of propylene and an α-olefin having 4 to 10 carbon atoms include a propylene-1-butene random copolymer, a propylene-1-hexene random copolymer, a propylene-1-octene random copolymer, a propylene-1-decene random copolymer, etc.

[0075] Examples of the random copolymer of propylene, ethylene and an α-olefin having 4 to 10 carbon atoms include a propylene-ethylene-1-butene copolymer, a propylene-ethylene-1-hexene copolymer, a propylene-ethylene-1-octene, a propylene-ethylene-1-decene copolymer, etc.

[0076] The propylene polymer can be produced using a known polymerization catalyst for olefins and a known polymerization method.

[0077] As polymerization catalysts, examples include: Ziegler-type catalyst systems; Ziegler-Natta-type catalyst systems; catalyst systems comprising a Group 4 transition metal compound having a cyclopentadienyl ring and an alkylaluminoxane; or catalyst systems comprising a Group 4 transition metal compound having a cyclopentadienyl ring, a compound that forms an ionic complex by reacting with the transition metal compound, and an organoaluminum compound; catalyst systems obtained by modifying inorganic particles such as silica and clay minerals by loading thereon catalyst components such as a Group 4 transition metal compound having a cyclopentadienyl ring, a compound that forms an ionic complex, and an organoaluminum compound, etc. Additionally, a prepolymerization catalyst prepared by prepolymerizing ethylene and an α-olefin in the presence of the above catalyst system can also be used.

[0078] From the viewpoint of molding and processing the pellets into various uses, when the total amount of the resin pellets is set to 100% by mass, the content of the polyolefin resin contained in the resin pellets of the present embodiment is preferably 98% to 99.9% by mass, more preferably 99.0% to 99.9% by mass.

[0079] (Lubricant)

[0080] The resin pellets of the present embodiment further contain erucamide and fatty acid amides having 20 or less carbon atoms. These erucamide and fatty acid amides having 20 or less carbon atoms can be added as lubricants during the manufacture of the resin pellets. By making the resin pellets contain erucamide and fatty acid amides having 20 or less carbon atoms, the slipperiness of the film made from the resin pellets becomes excellent.

[0081] When the amount of the polyolefin resin contained in the resin pellets is set to 100% by mass, the total amount of erucamide and fatty acid amides having 20 or less carbon atoms in the polyolefin resin pellets is preferably 200 ppm to 10,000 ppm by mass, preferably 400 ppm to 4,000 ppm by mass, and more preferably 500 ppm to 2,300 ppm by mass. By making the total amount of erucamide and fatty acid amides having 20 or less carbon atoms within the above range, the slipperiness of the film made from the resin pellets can be further improved.

[0082] (Erucamide)

[0083] Erucamide has the chemical formula CH3(CH2)7CH=CH(CH2) 11 CONH2 and is an organic fatty acid amide having 22 carbon atoms with one unsaturated bond.

[0084] When the amount of the polyolefin resin contained in the resin pellets is 100% by mass, the content of erucamide in the polyolefin resin pellets is preferably 200 ppm by mass to 10,000 ppm by mass, more preferably 400 ppm by mass to 4,000 ppm by mass, and still more preferably 500 ppm by mass to 2,300 ppm by mass. By making the content of erucamide within the above range, the slipperiness of the film produced from the resin pellets can be further improved.

[0085] (fatty acid amide having 20 or less carbon atoms)

[0086] In the polyolefin resin pellets of the present embodiment, when the total amount of erucamide and the fatty acid amide having 20 or less carbon atoms is 100% by mass, the content of the fatty acid amide having 20 or less carbon atoms is 1% by mass to 6% by mass. By making the content of the fatty acid amide having 20 or less carbon atoms within the above range, the fine powder generated from the resin pellets is reduced.

[0087] From the viewpoint of improving the slipperiness of the film produced from the resin pellets, when the total amount of erucamide and the fatty acid amide having 20 or less carbon atoms is 100% by mass, the lower limit value of the content of the fatty acid amide having 20 or less carbon atoms is preferably 1.1% by mass or more, more preferably 1.2% by mass or more, and still more preferably 1.3% by mass or more. In addition, from the viewpoint of further reducing the fine powder generated from the resin pellets, when the total amount of erucamide and the fatty acid amide having 20 or less carbon atoms is 100% by mass, the upper limit value of the content of the fatty acid amide having 20 or less carbon atoms is preferably 6% by mass or less, more preferably 5% by mass or less, and still more preferably 4% by mass or less. As a range, when the total amount of erucamide and the fatty acid amide having 20 or less carbon atoms is 100% by mass, the content of the fatty acid amide having 20 or less carbon atoms is 1% by mass to 6% by mass, more preferably 1.2% by mass to 5% by mass, and still more preferably 1.5% by mass to 4% by mass.

[0088] For the fatty acid amide having 20 or less carbon atoms, the number of carbon atoms of the fatty acid constituting it may be 20 or less. In addition, the number of carbon atoms of the fatty acid is preferably 8 or more, more preferably 10 or more. In addition, the fatty acid amide having 20 or less carbon atoms may be one fatty acid amide or a plurality of fatty acid amides, but a plurality of fatty acid amides are preferred.

[0089] The fatty acid amide having 20 or less carbon atoms may be an unsaturated fatty acid amide or a saturated fatty acid amide. As the fatty acid amide having 20 or less carbon atoms, from the viewpoint of suppressing the generation of fine powder of the resin pellets, it is preferably to contain both an unsaturated fatty acid amide and a saturated fatty acid amide.

[0090] As a fatty acid amide having 20 or less carbon atoms, when both an unsaturated fatty acid amide and a saturated fatty acid amide are included, it is preferable to adjust the content ratio of the unsaturated fatty acid amide to the saturated fatty acid amide. The ratio of the content of the unsaturated fatty acid amide contained in the fatty acid amide having 20 or less carbon atoms to the content of the saturated fatty acid amide is preferably 2 to 6. By containing the unsaturated fatty acid amide having 20 or less carbon atoms within the above range relative to the saturated fatty acid amide having 20 or less carbon atoms, the generation of fine powder of the resin pellets can be further suppressed. The ratio of the content of the unsaturated fatty acid amide to the content of the saturated fatty acid amide is more preferably 2 to 5, and further preferably 2 to 4. The ratio of the content of the unsaturated fatty acid amide to the content of the saturated fatty acid amide may be 3 to 6.

[0091] In addition, when the total amount of erucic acid amide and the fatty acid amide having 20 or less carbon atoms is 100% by mass, the content of the unsaturated fatty acid amide having 20 or less carbon atoms is preferably 1.0% by mass to 6.0% by mass, more preferably 1.0% by mass to 4.0% by mass, and further preferably 1.0% by mass to 2.0% by mass. By containing the unsaturated fatty acid amide having 20 or less carbon atoms within the above range, the generation of fine powder of the resin pellets can be further suppressed.

[0092] When the total amount of erucic acid amide and the fatty acid amide having 20 or less carbon atoms is 100% by mass, the content of the saturated fatty acid amide having 20 or less carbon atoms is preferably 0.3% by mass to 1.0% by mass, more preferably 0.3% by mass to 0.8% by mass, and further preferably 0.3% by mass to 0.5% by mass. By containing the saturated fatty acid amide having 20 or less carbon atoms within the above range, the generation of fine powder of the resin pellets can be further suppressed.

[0093] Examples of the unsaturated fatty acid amide having 20 or less carbon atoms include: palmitoleic acid amide, hexadecenoic acid amide, oleic acid amide, linoleic acid amide, gadoleic acid amide, eicosadienoic acid amide. Among them, as the unsaturated fatty acid amide, it is preferable to contain a monounsaturated fatty acid amide having one double bond, and it is preferable to contain one or more selected from oleic acid amide and gadoleic acid amide. Examples of the saturated fatty acid amide having 20 or less carbon atoms include: octanoic acid amide, nonanoic acid amide, decanoic acid amide, palmitic acid amide, stearic acid amide, arachidic acid amide. Among them, it is preferable to contain one or more selected from decanoic acid amide, palmitic acid amide, stearic acid amide, arachidic acid amide.

[0094] When oleic acid amide is included as an unsaturated fatty acid amide having 20 or less carbon atoms, when the total amount of erucic acid amide and fatty acid amide having 20 or less carbon atoms is set to 100% by mass, the content of oleic acid amide is preferably 0.05% by mass to 0.45% by mass, more preferably 0.2% by mass to 0.4% by mass.

[0095] When gadoleic acid amide is included as an unsaturated fatty acid amide having 20 or less carbon atoms, when the total amount of erucic acid amide and fatty acid amide having 20 or less carbon atoms is set to 100% by mass, the content of gadoleic acid amide is preferably 0.5% by mass to 5.0% by mass, more preferably 0.5% by mass to 3.0% by mass, and further preferably 0.5% by mass to 1.5% by mass. When the total amount of erucic acid amide and fatty acid amide having 20 or less carbon atoms is set to 100% by mass, the content of gadoleic acid amide can be 0.8% by mass to 2.0% by mass.

[0096] When palmitic acid amide is included as a saturated fatty acid amide having 20 or less carbon atoms, when the total amount of erucic acid amide and fatty acid amide having 20 or less carbon atoms is set to 100% by mass, the content of palmitic acid amide is preferably 0% by mass to 0.15% by mass, more preferably 0% by mass to 0.1% by mass. When the total amount of erucic acid amide and fatty acid amide having 20 or less carbon atoms is set to 100% by mass, the content of palmitic acid amide can be 0.01% by mass to 0.1% by mass. When the total amount of erucic acid amide and fatty acid amide having 20 or less carbon atoms is set to 100% by mass, the content of palmitic acid amide can be 0.1% by mass or less. The pellets may not contain palmitic acid amide.

[0097] When stearic acid amide is included as a saturated fatty acid amide having 20 or less carbon atoms, when the total amount of erucic acid amide and fatty acid amide having 20 or less carbon atoms is set to 100% by mass, the content of stearic acid amide is preferably 0% by mass to 0.20% by mass, more preferably 0% by mass to 0.15% by mass, and further preferably 0% by mass to 0.10% by mass. When the total amount of erucic acid amide and fatty acid amide having 20 or less carbon atoms is set to 100% by mass, the content of stearic acid amide can be 0.01% by mass to 0.10% by mass. When the total amount of erucic acid amide and fatty acid amide having 20 or less carbon atoms is set to 100% by mass, the content of stearic acid amide can be 0.1% by mass or less.

[0098] When erucamide and fatty acid amides having 20 or less carbon atoms are used in combination with arachidic acid amide as an unsaturated fatty acid amide having 20 or less carbon atoms, and the total amount of erucamide and fatty acid amides having 20 or less carbon atoms is 100% by mass, the content of arachidic acid amide is preferably 0.2% to 0.6% by mass, more preferably 0.2% to 0.5% by mass, and still more preferably 0.3% to 0.4% by mass.

[0099] (Fatty acid amides having 22 or more carbon atoms)

[0100] In addition to erucamide and fatty acid amides having 20 or less carbon atoms, the polyolefin resin pellets of the present embodiment may further contain fatty acid amides having 22 or more carbon atoms other than erucamide. By including fatty acid amides having 22 or more carbon atoms other than erucamide, the slipperiness of the resulting film can be improved. As the fatty acid amides having 22 or more carbon atoms, those having 22 to 24 carbon atoms are preferred. The fatty acid amides having 22 or more carbon atoms other than erucamide may be one kind, may be a plurality of kinds, may be unsaturated fatty acid amides, or may be saturated fatty acid amides. As the fatty acid amides having 22 or more carbon atoms other than erucic acid, one or more selected from the group consisting of behenic acid amide, selacholeic acid amide, and lignoceric acid amide are preferred.

[0101] (Other additives)

[0102] In addition to the above polyolefin resin and fatty acid amide, the polyolefin resin pellets of the present embodiment may further contain additives. Examples of such additives include antioxidants, surfactants, weathering agents, anti-blocking agents, antistatic agents, antifogging agents, anti-dripping agents, pigments, fillers, etc. In addition, as the additive, a lubricant other than the above fatty acid amide may be contained. When the amount of the polyolefin resin contained in the resin pellets is 100% by mass, the total content of the additives in the polyolefin resin pellets is preferably 1% by mass or less.

[0103] (Shape of resin pellets, etc.)

[0104] The shape of the resin pellets of the present embodiment is not particularly limited, and may be angular, spherical, cylindrical, ellipsoidal, or polygonal. Among them, from the viewpoint of suppressing the occurrence of grinding of the resin pellets and reducing the generation of fine powder, a spherical shape is preferred. The spherical shape mentioned here includes not only a perfect spherical shape but also an approximate spherical shape, an approximate ellipsoidal shape, and an approximate rice grain shape.

[0105] There is no particular limitation on the size of the resin pellets. However, from the viewpoints of suppressing the occurrence of grinding of the resin pellets and the moldability of the resin pellets, the average minor axis of the resin pellets is preferably 1 mm to 7 mm. Herein, the minor axis refers to the shortest diameter of the pellets. The average minor axis of the resin pellets is more preferably 1 mm to 5 mm, and further preferably 1.5 mm to 3.5 mm. In addition, from the same viewpoints, the average major axis of the resin pellets is preferably 3 mm to 10 mm. Herein, the major axis refers to the longest diameter of the pellets. The average major axis of the resin pellets is more preferably 3 mm to 8 mm, and further preferably 4 mm to 6 mm.

[0106] From the same viewpoints, the average weight of the resin pellets is preferably 30 mg to 100 mg, more preferably 30 mg to 80 mg, and further preferably 40 mg to 60 mg.

[0107] From the same viewpoints, the average volume of the resin pellets is preferably 30 mm 3 to 100 mm 3 and more preferably 30 mm 3 to 80 mm 3 and further preferably 40 mm 3 to 60 mm 3 .

[0108] From the same viewpoints, the average surface area of the resin pellets is preferably 40 mm 2 to 200 mm 2 and more preferably 40 mm 2 to 150 mm 2 and further preferably 60 mm 2 to 100 mm 2 .

[0109] (Use of the resin pellets)

[0110] The resin pellets of the present embodiment produce less fine powder, and subsequent molding processing becomes easier. The resin pellets of the present embodiment can be mixed with any other components as needed, and then formed into a molded article having a desired shape by a known molding method such as extrusion molding, injection molding, blow molding, compression molding, stretching, vacuum molding, etc. There is no particular limitation on the molded article, and examples thereof include films, sheets, laminated films, laminated sheets, laminated products, tubes, hoses, conduits, hollow containers, bottles, fibers, and various shaped parts.

[0111] <Manufacturing method of the resin pellets>

[0112] Next, an example of the method for manufacturing the above resin pellets will be described. The above resin pellets can be manufactured, for example, by a method comprising a step of mixing a polyolefin resin and a lubricant to obtain a mixture, and a step of melt-extruding the obtained mixture to obtain resin pellets.

[0113] As the polyolefin resin, the above polyolefin resin can be used, and as the lubricant mixed with the polyolefin resin, the above lubricant can be used. The lubricant contains erucic acid amide and a fatty acid amide having 20 or less carbon atoms. When the total amount of erucic acid amide and the fatty acid amide having 20 or less carbon atoms is 100% by mass, the content of the fatty acid amide having 20 or less carbon atoms is 1% to 6% by mass.

[0114] In the step of mixing the polyolefin resin and the lubricant to obtain a mixture, for example, a certain amount of the polyolefin resin and the lubricant are supplied into an extruder by a feeder or the like and mixed in the extruder to obtain a mixture of the polyolefin resin and the lubricant. As the extruder, for example, a single-screw extruder, a twin-screw extruder, etc. can be used.

[0115] In the extruder, the mixture of the polyolefin resin and the lubricant can be melt-kneaded as needed. The temperature of the melt-kneading is preferably 140°C to 300°C, more preferably 140°C to 220°C.

[0116] When other components other than the polyolefin and the lubricant are incorporated into the resin pellets, by supplying the other components into the extruder, they can be mixed with the polyolefin resin and the lubricant to form a mixture.

[0117] Next, the obtained mixture is melt-extruded from the through-holes of the die into a strand shape.

[0118] As the shape of the through-holes of the die, for example, a circle, an ellipse, a polygon, a star, a semi-circle, a semi-ellipse, a rounded rectangle, etc. can be cited. Among them, the shape of the die hole is preferably a circle or an ellipse.

[0119] The extrusion conditions such as the extrusion linear velocity, the extrusion amount, and the extrusion pressure of the mixture can be appropriately set.

[0120] The extruded strand-shaped mixture can be cooled and solidified. Water or the like can be used as the cooling medium. The cooling conditions such as the temperature of the cooling medium and the flow rate of the cooling medium can be appropriately set, and the degree of cooling only needs to be solidified to the extent that the extruded mixture can be cut off.

[0121] While cooling and solidifying the mixture in parallel with the extrusion and cutting the solidified strand-shaped mixture, pellets can be obtained. For cutting, a tool such as a rotary cutter can be used.

[0122] If necessary, the resin pellets obtained by cutting can be transported to subsequent processes such as drying, foreign matter removal, and packaging. The resin pellets can be transported to the subsequent processes through an air conveying pipeline.

[0123] In the air conveying pipeline, from the viewpoint of suppressing the generation of fine powder, it is preferable to transport the resin pellets at a speed of 8 tons / hour to 20 tons / hour, and more preferably at a speed of 8 tons / hour to 12 tons / hour.

[0124] A pneumatic separation device for separating the resin pellets and fine powder can be provided on the air conveying pipeline to separate and remove the generated fine powder from the resin pellets.

[0125] It should be noted that the resin pellets of the present embodiment can be manufactured by methods other than the above-described embodiments.

[0126] Examples

[0127] <Example 1>

[0128] (Manufacture of Resin Pellets)

[0129] 80% by mass of ethylene-1-butene-1-hexene copolymer (manufactured by Sumitomo Chemical Co., Ltd., Sumikasen EP, melt flow rate: 1.0 g / 10 minutes, density: 919 kg / m 3 )、20 mass% of high-pressure low-density polyethylene (manufactured by Sumitomo Chemical Co., Ltd., Sumikasen, melt flow rate: 4.0 g / 10 minutes, density: 923 kg / m 3 ), 600 mass ppm of lubricant A having the composition shown in Table 1-1, 750 mass ppm of antioxidant (manufactured by Sumitomo Chemical Co., Ltd., Sumilizer GP), and 700 mass ppm of anti-blocking agent (manufactured by Mizusawa Chemical Industry Co., Ltd., Shilton JC-50) were mixed, supplied to an extruder, and melt-kneaded. The molten mixture was extruded through the through-holes of the die and cut while being solidified with cooling water, thereby manufacturing rice-grain-shaped resin pellets.

[0130] (Measurement of Fine Powder Ratio)

[0131] The manufactured resin pellets were pneumatically conveyed at a speed of 10 tons / hour to 20 tons / hour through a 10-inch knurled pipe for air conveyance. The pipe had a pneumatic separation device for separating the pellets and fine powder in the middle. The pneumatically conveyed pellets were again separated into pellets and fine powder by a pneumatic separation device (Jet Separator CFS-150 manufactured by Accor Co., Ltd.), and the fine powder ratio was calculated according to the following formula.

[0132] Fine powder ratio (ppm by mass) = Fine powder mass / Granular material mass

[0133] (Film forming)

[0134] Using a blown film forming machine manufactured by PLACO Co., Ltd. (a full-threaded single-screw extruder (diameter 30 mm φ, L / D = 28), a die (die diameter 50 mm φ, die lip gap 0.8 mm), a double-slit air ring), under the processing conditions of a processing temperature of 170 °C, an extrusion rate of 5.5 kg / hour, a frost line distance (FLD) of 200 mm, and a blow-up ratio of 1.8, the granular material before air transportation was formed into a film with a thickness of 50 μm. For the slipperiness of the obtained film, the friction angle tanθ was measured by the following method.

[0135] (Measurement of friction angle tanθ (slipperiness))

[0136] Using a friction angle measuring instrument manufactured by Toyo Seiki Co., Ltd., a sample film of 160 mm (length) × 80 mm (width) was placed on an inclined plate, and a 1 kg screw with a length of 100 mm (length) × 65 mm (width) on which the sample film was mounted was placed below. The angle θ at which the screw started to move at an inclined rising speed of 2.7 ° / second was measured, and the values of tanθ are shown in Table 2. The smaller the value of tanθ, the better the slipperiness.

[0137] (Analysis of the composition of the lubricant)

[0138] For the composition of the lubricant used in the manufacture of resin granules, the mass ratio of each compound was measured using a gas chromatograph equipped with a hydrogen flame ionization detector (FID) (hydrogen flame ionization detector) and is shown in Table 1-1.

[0139] <Examples 2 to 4, Comparative Example 1>

[0140] Except for using lubricant B (Example 2), lubricant C (Example 3), lubricant D (Example 4), lubricant E (Comparative Example 1), lubricant F (Example 5), and lubricant G (Example 6) with the compositions shown in Table 1-1 or Table 1-2 instead of lubricant A, resin granules were manufactured in the same manner as in Example 1, films were formed from the resin granules, and the fine powder ratio and the friction angle tanθ were measured respectively.

[0141] Table 1-1

[0142]

[0143] Table 1-2

[0144]

[0145] It should be noted that for the columns recorded as "<0.1>" and "N.D." in Table 1-1 and Table 1-2, the numerical values are set to 0, the numerical values of a to d are calculated, and recorded in Table 1-1 and Table 1-2.

[0146] Table 2

[0147] Lubricant type Fine powder rate (mass ppm) Slipperiness of the film (tanθ) Example 1 Lubricant A 5 0.32 Example 2 Lubricant B 4 0.32 Example 3 Lubricant C 4 0.33 Example 4 Lubricant D ※ 0.36 Example 5 Lubricant F 2 0.33 Example 6 Lubricant G 2 0.33 Comparative Example 1 Lubricant E 19 –

[0148] It should be noted that the fine powder ratio of Example 4 recorded as "※" in Table 2 can be predicted to be the same level as that of Examples 1 to 3.

[0149] As shown in Table 2, in the resin pellets of Examples 1 to 4, 5, and 6, the amount of fine powder generated from the resin pellets is small. On the other hand, in Example 2 using Lubricant B with a higher content of fatty acid amide having 20 or less carbon atoms than Lubricant D, excellent slipperiness of the film was obtained compared to Example 4 using Lubricant D.

Claims

1. A pellet, which is a polyolefin resin pellet containing a polyolefin resin, erucamide, and a fatty acid amide having 20 or less carbon atoms, wherein when the total amount of the erucamide and the fatty acid amide having 20 or less carbon atoms is set to 100% by mass, the content of the fatty acid amide having 20 or less carbon atoms is 1% to 6% by mass, the fatty acid amide having 20 or less carbon atoms contains both an unsaturated fatty acid amide and a saturated fatty acid amide, when the total amount of the erucamide and the fatty acid amide having 20 or less carbon atoms is set to 100% by mass, the content of the unsaturated fatty acid amide having 20 or less carbon atoms is 1.0% to 6.0% by mass, when the total amount of the erucamide and the fatty acid amide having 20 or less carbon atoms is set to 100% by mass, the content of the saturated fatty acid amide having 20 or less carbon atoms is 0.3% to 1.0% by mass.

2. The pellet according to claim 1, wherein, The polyolefin resin is one or more selected from polyethylene resins and polypropylene resins.

3. The pellet according to claim 1 or 2, wherein The ratio of the content of the unsaturated fatty acid amide contained in the fatty acid amide having 20 or less carbon atoms to the content of the saturated fatty acid amide is 2 to 6.

4. The pellet according to claim 1 or 2, wherein, The unsaturated fatty acid amide is a monounsaturated fatty acid amide.

5. The pellet according to claim 1 or 2, wherein, The unsaturated fatty acid amide is one or more selected from oleamide and gadoleic acid amide.

6. The pellet according to claim 1 or 2, wherein, The saturated fatty acid amide is one or two or more selected from the group consisting of capric acid amide, palmitic acid amide, stearic acid amide, and arachidic acid amide.

7. The pellet according to claim 1 or 2, wherein, The pellet further contains a fatty acid amide having 22 or more carbon atoms other than erucamide.

8. The pellet according to claim 7, wherein The fatty acid amide having 22 or more carbon atoms is one or two or more selected from the group consisting of behenic acid amide, selacholeic acid amide, and lignoceric acid amide.

9. The pellet according to claim 1 or 2, wherein, The upper limit of the content of the fatty acid amide having 20 or less carbon atoms is 4% by mass.

10. A method for manufacturing a resin pellet, which is a method for manufacturing the polyolefin resin pellet according to any one of claims 1 to 9, wherein the method for manufacturing the resin pellet includes: a step of mixing a polyolefin resin and a lubricant to obtain a mixture, and a step of melt-extruding the mixture to obtain a resin pellet, the lubricant contains erucamide and a fatty acid amide having 20 or less carbon atoms, and when the total amount of the erucamide and the fatty acid amide having 20 or less carbon atoms is set to 100% by mass, the content of the fatty acid amide having 20 or less carbon atoms is 1% to 6% by mass.

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